Scythes, sickles and other blades: defining the diversity of pectoral fin morphotypes in Pachycormiformes

Authors: 1,2,3,4, 5, 6, 7, 8,9,10, 11,12,13

Vertebrate Palaeontology, SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Bavaria, Germany Palaeobiology, Department of Natural Sciences, National Museums Scotland, Edinburgh, Scotland School of Earth Sciences, University of Bristol, Bristol, England Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland Rocky Mountain Dinosaur Resource Center, Woodland Park, CO, USA Universiteitsmuseum Utrecht, Utrecht University, Utrecht, Netherlands Centre de Recherche Scientifique/Paléontologie, Musée national d’histoire naturelle de Luxembourg, Luxembourg, Luxembourg Division of Paleontology, American Museum of Natural History, New York, NY, USA Department of Anthropology, Lehman College, City University of New York, New York, NY, USA Department of Anthropology, The Graduate Center, City University of New York, New York, NY, USA Sektion Mammalogie, Zoologische Staatssammlung München, Staatliche Naturwissenschaftliche Sammlungen Bayerns, Munich, Germany GeoBio-Center, Ludwig-Maximilians-Universität München, Munich, Germany Department Biologie II, Ludwig-Maximilians-Universität München, Munich, Germany

Source: Liston, J.J., A.E. Maltese, P.H. Lambers, D. Delsate, W.E.H. Harcourt-Smith, A.H. van Heteren, 2019. – Scythes, sickles and other blades: defining the diversity of pectoral fin morphotypes in Pachycormiformes. – PeerJ 7:e7675 https://doi.org/10.7717/peerj.7675

Abstract: The traditional terminology of ‘scythe’ or ‘sickle’ shaped is observed to be flawed as an effective descriptor for pectoral fin shape in pachycormids. The diversity of pachycormid pectoral fin shapes is assessed across the 14 recognised genera that preserve complete pectoral fins, and improved terms are defined to more effectively describe their form, supported by anatomical observation and aspect ratio analysis of individual fins, and corroborated by landmark analysis. Three clear and distinct pectoral fin structural morphotypes emerge (falceform, gladiform, falcataform), reflecting a diversity of pachycormid lifestyles throughout the Mesozoic, from agile pursuit predator to slow-cruising suspension feeder.